Breastfeeding is a high-risk activity for mother-to-child transmission of HIV. In many underdeveloped countries, breastfeeding is the common practice due to cultural, religious, health and economical reasons. Thus there is a need to develop safer methods to provide the infants the benefits of human milk without the risk of acquiring HIV. Our purpose is to study inactivation of HIV in human milk by an alkyl sulfate microbicide called sodium dodecyl sulfate (SDS). SDS is an anionic detergent with surfactant properties and, additionally, it denatures proteins. It has low toxicity, low bioavailability and it inactivates HIV in vitro. Milk from healthy donors will be infected with HIV and treated with 1 % or 0.1 % SDS and then further analyzed for viral activity and its nutritional and protective functions before and after SDS removal from the sample. Different methods for SDS removal will be tested. Protein recovery after this process will be assessed by SDS- Polyacrylamide Gel Electrophoresis (SDS-PAGE) and by Lowry analyses. Creamatocrit determinations will reflect the milk's fat concentration and energy content. Antibody quantitation and function will be studied by rocket immunoelectrophoresis, ELISA and by immunoturbodimetric quantitation with Roche(R) /Hitachi(R) Modular machine. Other important enzymatic functions will also be analyzed (e.g., lactoferrin, lysozyme). Infectivity assays on indicator cells will allow study of inactivation of the virus. In vivo toxicity studies will be performed in ICR outbred mice.